Recently, modality for use in medical inspection, such as CT or MRI is often employed in medical care. There is an increasing desire for enhancement of performance of silver halide photographic light sensitive materials used for outputting images photographed by these instruments, and to enhance sharpness of the image, in particular, a photographic material with high contrast is strongly desired.
As one of technique for increasing contrast is known a method of increasing silver coverage. However, this method is not preferable, since it results in marked reduction of contrast in cases when it is rapidly processed over short periods of time of not more than 60 sec or processed at a low developer or fixer replenishing rate.
As another technique for increasing contrast is known a method of reducing a gelatin content used as binder in the photographic material to enhance processability thereof. However, reduction of the binder often produces streak-like fogging (socalled roller marks) when processed in an automatic processor, resulting in undesirable deterioration of pressure resistance.
Recently, as silver halide grain emulsion grains capable of giving highly efficient spectral sensitization, high silver-covering power and high contrast is known tabular silver halide grains. However, the tabular silver halide grains have the disadvantage that the silver image tone is not a neutral black but yellowish one, giving an unpleasant impression of the silver image. Such a phenomenon often occurs with a fine grain emulsion or thin tabular grain emulsion, and an attempt of modification with a toning agent is disclosed. However, application of conventional toning agents to a high sensitive silver halide emulsion results in marked desensitization so that it is not preferred for practical use.
In silver halide photographic light sensitive materials for medical use, an image with a low contrast becomes a flat image, resulting in marked lowering of sharpness. It is usual to finish up a clear image by blackening the background of the images used for such diagnosis. A photographic material with a low contrast lowers the background density, resulting in unacceptable blurred images. Further, bibliographical data such as the patient's name, photographing date and an examining division are usually written onto the film. When a photographic material with low contrast is used, letters are often unclear and therefore hard to read.
In the medical first aid, prompt treatments are indispensable for grasp conditions of a patient so that super rapid treatment system with a total treatment time of 30 sec. is achieved. In addition, there are desired improvements in the processing system, such as reduction of processing effluent by lowering the replenishing rate and minimizing the processing work in terms of environmental protection. Therefore, there is a strong desire for a silver halide photographic light sensitive material in which high sensitivity and high contrast can be consistently achieved even when subjected to rapid processing, neutral black image tone can be obtained and there is no need for concern in terms of environmental protection, and a processing method thereof.